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Urun S, Şirin E. Determination of the effect of pre-mating weight and placental characteristics on birth weight in Karayaka sheep. Arch Anim Breed 2023; 66:335-340. [PMID: 38111386 PMCID: PMC10726019 DOI: 10.5194/aab-66-335-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/10/2023] [Indexed: 12/20/2023] Open
Abstract
The aim of this study was to determine the effect of the pre-mating weight and placental characteristics on birth weight. Data were collected from 62 Karayaka ewes and 70 Karayaka lambs. The placental characteristics considered were placental weight, placental area and the number of cotyledons. The Pearson correlation coefficient was used for statistical comparison and the determination of relationships between variables. In addition, correlation coefficients between live weights and placental characteristics were determined. The average birth weight (BW), pre-mating weight (PMW), placental weight (PW), placental area (PA) and cotyledon number (CN) values were 4.37 ± 0.70 kg, 50.22 ± 5.63 kg, 362.51 ± 118.42 g, 994.18 ± 312.76 cm2 and 56.93 ± 8.06, respectively. BW had positive correlations with PMW (0.147), birth type (BT) (0.643), PW (0.604), PA (0.323) and CN (0.161) (P < 0.05). BW had negative correlations with maternal age (MA) (- 0.119 ) (P < 0.05). PMW had positive correlations with maternal age (MA) (0.237) (P < 0.05). PMW had negative correlations with S (sex) (- 0.003 ), PW (- 0.049 ), PA (- 0.067 ) and CN (- 0.080 ) (P > 0.05).
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Affiliation(s)
- Samet Urun
- Department of Agricultural Biotechnology, Faculty of Agriculture, Kırşehir Ahi Evran University, 40100 Kırşehir, Türkiye
| | - Emre Şirin
- Department of Agricultural Biotechnology, Faculty of Agriculture, Kırşehir Ahi Evran University, 40100 Kırşehir, Türkiye
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2
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Breeding Ewe Lambs: An Australasian Perspective. Animals (Basel) 2022; 12:ani12223207. [PMID: 36428434 PMCID: PMC9686899 DOI: 10.3390/ani12223207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/04/2022] [Accepted: 11/12/2022] [Indexed: 11/22/2022] Open
Abstract
A number of potential advantages have been identified for breeding ewe lambs at 7 to 9 months of age, including increased lifetime productivity and profitability. However, breeding at this young age in extensive pastoral systems, such as in Australasia, can be associated with a number of disadvantages resulting in uptake of this management procedure being relatively low. This review highlights the known differences between ewe lamb and mature ewe reproductive performance, thus differing in their management. The review then summaries the scientific literature of factors that affect ewe lamb reproductive success, with a focus on recent studies conducted under extensive pasture-based conditions in Australasia. In particular, this review outlines the importance of ewe lamb live weight and body condition score on their productivity. The potential long-term consequences of breeding a ewe lamb at a young age in terms of her future success and that of her offspring to weaning are briefly outlined. In addition, the potential impacts of selecting progeny born to ewe lambs as future replacement ewes are discussed. Throughout this review, optimal management guidelines from prior to breeding the ewe lambs until rebreeding at 2 years of age are provided. Lastly, areas requiring future research are identified and discussed.
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Clune T, Bruce M, Glanville E, Campbell AJD, Lockwood A, Hancock S, Thompson AN, Beetson S, Brookes D, Trengove C, O'Handley R, Jacobson C. Seropositivity to
Campylobacter
and association with abortion and lamb mortality in maiden ewes from Western Australia, South Australia and Victoria. Aust Vet J 2022; 100:397-406. [PMID: 35665919 PMCID: PMC9544749 DOI: 10.1111/avj.13173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/27/2022] [Accepted: 05/01/2022] [Indexed: 11/29/2022]
Abstract
This case‐control study investigated associations between Campylobacter fetus or Campylobacter jejuni titre and reproductive outcomes in 22 flocks of Merino and non‐Merino maiden ewes aged 1–2 years old. Campylobacter titres were also determined for multiparous ewes aged 3 years or older on the same farms. C. fetus ‘positivity’ (titre ≥1:80) was detected for 12% (57/462; 95% confidence interval [95% CI] 9.6 to 15.6) of maiden ewes and 31% (65/210; 95% CI 25.0 to 37.4) of mature ewes. The odds for failing to rear a lamb in C. fetus‐‘exposed’ maiden ewes (titre ≥1:10) was 2.01 times that of seronegative ewes (95% CI 1.09 to 3.77; P = 0.027), but there was no association between C. fetus‐‘positivity’ (titre ≥1:80) and failure to rise (OR 1.69; 95% CI 0.77 to 3.76; P = 0.191). C. fetus abortions were confirmed with microbial culture in one maiden ewe flock. In this flock, C. fetus titres fluctuated and often waned by lamb marking, highlighting the value of necropsies during abortion investigations. C. jejuni‐‘positivity’ (titre ≥1:80) was detected for 44% (204/462; 95% CI 39.7 to 48.7) maiden ewes, but odds of failing to rear were decreased for C. jejuni‐‘positive’ ewes (OR 0.52; 95% CI 0.32 to 0.83; P = 0.007). The association between Campylobacter serology and the reproductive outcome was inconsistent in these flocks. Serology should be considered in the context of other risk factors and used in conjunction with other strategies to investigate the impact of Campylobacter exposure on ewe reproductive performance such as monitoring for abortions and lamb necropsies to determine aetiological diagnosis, and vaccination trials.
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Affiliation(s)
- T Clune
- Centre for Animal Production and Health, Food Futures Institute Murdoch University South Street Murdoch Western Australia 6150 Australia
| | - M Bruce
- Centre for Biosecurity and One Health, Harry Butler Institute Murdoch University South Street Murdoch Western Australia 6150 Australia
| | - E Glanville
- Mackinnon Project, Faculty of Veterinary and Agricultural Sciences University of Melbourne Werribee Victoria 3030 Australia
| | - AJD Campbell
- Nossal Institute for Global Health, Melbourne School of Population and Global Health University of Melbourne Melbourne Victoria 3010 Australia
| | - A Lockwood
- Centre for Animal Production and Health, Food Futures Institute Murdoch University South Street Murdoch Western Australia 6150 Australia
| | - S Hancock
- Centre for Animal Production and Health, Food Futures Institute Murdoch University South Street Murdoch Western Australia 6150 Australia
| | - AN Thompson
- Centre for Animal Production and Health, Food Futures Institute Murdoch University South Street Murdoch Western Australia 6150 Australia
| | - S Beetson
- Centre for Animal Production and Health, Food Futures Institute Murdoch University South Street Murdoch Western Australia 6150 Australia
| | - D Brookes
- Mackinnon Project, Faculty of Veterinary and Agricultural Sciences University of Melbourne Werribee Victoria 3030 Australia
| | - C Trengove
- School of Animal and Veterinary Sciences University of Adelaide Roseworthy South Australia 5371 Australia
| | - R O'Handley
- School of Animal and Veterinary Sciences University of Adelaide Roseworthy South Australia 5371 Australia
| | - C Jacobson
- Centre for Animal Production and Health, Food Futures Institute Murdoch University South Street Murdoch Western Australia 6150 Australia
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Clune T, Lockwood A, Hancock S, Thompson AN, Bruce M, Beetson S, Campbell AJ, Glanville E, Brookes D, Trengove C, O’Handley R, Jacobson C. Toxoplasma gondii is not an important contributor to poor reproductive performance of primiparous ewes from southern Australia: a prospective cohort study. BMC Vet Res 2022; 18:109. [PMID: 35305646 PMCID: PMC8933891 DOI: 10.1186/s12917-022-03211-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 03/10/2022] [Indexed: 11/15/2022] Open
Abstract
Background Toxoplasma gondii causes reproductive losses in sheep worldwide, including Australia. The reproductive performance of primiparous ewes is typically lower than for mature, multiparous ewes, and younger ewes are more likely to be immunologically naïve and therefore more susceptible to reproductive disease if T. gondii infection occurs during pregnancy. The aim of this study was to assess the impact of infection with T. gondii on the reproductive performance of primiparous ewes in southern Australia using a prospective cohort study. This will inform the need for targeted control strategies for T. gondii in Australian sheep. Results Toxoplasma gondii seropositivity using indirect ELISA was detected at 16/28 farms located across southern Australia. Apparent seropositivity to T. gondii was lower in primiparous ewes (1.1, 95% confidence interval (CI) 0.6, 1.8) compared to mature, multiparous ewes (8.1, 95% CI 6.0, 10.5; P < 0.001). Toxoplasma gondii seroconversion during the gestation and lambing period was confirmed for 11/1097 (1.0, 95% CI 0.5, 1.7) of pregnant primiparous ewes that failed to raise a lamb, and 1/161 (0.6, 95% CI 0.1, 2.9) primiparous ewes with confirmed mid-pregnancy abortion. Conclusions Low frequency of detection of T. gondii seroconversion during gestation and low frequency of seropositivity to T. gondii suggests that toxoplasmosis was not an important contributor to reproductive losses in primiparous ewes on farms located over a wide geographical area in southern Australia. Supplementary Information The online version contains supplementary material available at 10.1186/s12917-022-03211-w.
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Pool KR, Chazal F, Smith JT, Blache D. Estrogenic Pastures: A Source of Endocrine Disruption in Sheep Reproduction. Front Endocrinol (Lausanne) 2022; 13:880861. [PMID: 35574027 PMCID: PMC9097266 DOI: 10.3389/fendo.2022.880861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 03/25/2022] [Indexed: 11/13/2022] Open
Abstract
Phytoestrogens can impact on reproductive health due to their structural similarity to estradiol. Initially identified in sheep consuming estrogenic pasture, phytoestrogens are known to influence reproductive capacity in numerous species. Estrogenic pastures continue to persist in sheep production systems, yet there has been little headway in our understanding of the underlying mechanisms that link phytoestrogens with compromised reproduction in sheep. Here we review the known and postulated actions of phytoestrogens on reproduction, with particular focus on competitive binding with nuclear and non-nuclear estrogen receptors, modifications to the epigenome, and the downstream impacts on normal physiological function. The review examines the evidence that phytoestrogens cause reproductive dysfunction in both the sexes, and that outcomes depend on the developmental period when an individual is exposed to phytoestrogen.
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Abortion and Lamb Mortality between Pregnancy Scanning and Lamb Marking for Maiden Ewes in Southern Australia. Animals (Basel) 2021; 12:ani12010010. [PMID: 35011116 PMCID: PMC8749747 DOI: 10.3390/ani12010010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/24/2021] [Accepted: 11/29/2021] [Indexed: 12/01/2022] Open
Abstract
Simple Summary The reproductive efficiency of ewes in their first breeding season (maiden ewes) can be inconsistent and disappointing. The frequency of abortion and its relative contribution to lamb losses in maiden ewe flocks in Australia has not been well studied. This study measured abortion and lamb mortality occurring between pregnancy diagnosis (scanning) and lamb marking in 30 flocks of maiden ewes on Australian sheep farms. The study included flocks of ewe lambs that had lambed for the first time at approximately one-year-old (n = 19) and two-tooth ewes that had lambed for the first time at two-years-old (n = 11). Abortion was detected in 14/19 flocks of ewe lambs and 6/11 flocks of two-tooth ewes using repeated scans. On average 5.7% of ewe lambs and 0.9% of two-tooth ewes aborted; however, abortion rates between flocks ranged from 0–50% for ewe lambs and 0–4.4% for two-tooth ewes. Lamb mortality from birth to marking represented the greatest contributor to overall lamb mortality occurring after pregnancy scanning but abortions were an important contributor to the overall losses in some ewe lamb flocks. This study highlights the variability in reproductive performance for maiden ewes and indicates that addressing losses due to abortion may improve reproductive performance in some ewe lamb flocks. Abstract The contribution of abortions to the overall mortality of lambs born to maiden (primiparous) ewes in Australia remains unclear. This cohort study aimed to quantify abortion and lamb mortality for ewe lambs and maiden Merino two-tooth ewes. Lamb mortality from pregnancy scanning to marking were determined for 19 ewe lamb and 11 Merino two-tooth ewe flocks across southern Australia. Average lamb mortality from scanning to marking was 35.8% (range 14.3–71.1%) for the ewe lambs and 29.4% (range 19.7–52.7%) for the two-tooth ewes. Mid-pregnancy abortion was detected in 5.7% of ewes (range 0–50%) in the ewe lamb flocks and 0.9% of ewes (range 0–4.4%) in the two-tooth ewe flocks. Mid-pregnancy abortion affecting ≥2% of ewes was observed in 6/19 ewe lamb flocks and 2/11 two-tooth ewe flocks. Lamb mortality from birth to marking represented the greatest contributor to foetal and lamb mortality after scanning, but mid-pregnancy abortion was an important contributor to lamb mortality in some ewe lamb flocks. Variability between the flocks indicates scope to improve the overall reproductive performance for maiden ewes by reducing foetal and lamb losses. Addressing mid-pregnancy abortion may improve the reproductive performance in some flocks.
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7
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Determining the Impact of Hogget Breeding Performance on Profitability under a Fixed Feed Supply Scenario in New Zealand. Animals (Basel) 2021; 11:ani11051303. [PMID: 33946604 PMCID: PMC8147200 DOI: 10.3390/ani11051303] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 11/21/2022] Open
Abstract
Simple Summary In New Zealand, hoggets (female lambs aged 4 to 16 months) can be bred at 8 to 9 months of age to produce a lamb. Breeding hoggets may improve farm production and profit but their levels of production are highly variable. This study modelled ewe flocks with combinations of hogget and mature ewe production levels to investigate changes in production and profit with hogget breeding. Firstly, breeding hoggets was profitable even when hogget production levels were as low as 0.26 lambs weaned per hogget. Secondly, improving mature ewe production levels was more beneficial for profit than larger improvements in hogget production levels. Thirdly, the highest profit was achieved when a flock had both very high mature ewe and hogget production levels. Fourthly, there was a mature ewe production level with which profit was the same for a flock without hogget breeding compared with a flock achieving New Zealand industry average hogget and mature ewe production levels. Overall, the relative profit levels achieved by the modelled flocks suggest more farmers should consider breeding hoggets but improving mature ewe production levels should be prioritised. 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 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.
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8
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McGovern FM, McHugh N, Fitzmaurice S, Pabiou T, McDermott K, Wall E, Fetherstone N. Phenotypic factors associated with lamb live weight and carcass composition measurements in an Irish multi-breed sheep population. Transl Anim Sci 2021; 4:txaa206. [PMID: 33409463 PMCID: PMC7758996 DOI: 10.1093/tas/txaa206] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 11/09/2020] [Indexed: 11/13/2022] Open
Abstract
Understanding the phenotypic factors that affect lamb live weight and carcass composition is imperative to generating accurate genetic evaluations and further enables implementation of functional management strategies. This study investigated phenotypic factors affecting live weight across the growing season and traits associated with carcass composition in lambs from a multibreed sheep population. Four live weight traits and two carcass composition traits were considered for analysis namely; birth, preweaning, weaning, and postweaning weight, and ultrasound muscle depth and fat depth. A total of 427,927 records from 159,492 lambs collected from 775 flocks between the years 2016 and 2019, inclusive were available from the Irish national sheep database. Factors associated with live weight and carcass composition were determined using linear mixed models. The heaviest birth, preweaning, and weaning weights were associated with single born lambs (P < 0.001), however by postweaning, there was no difference observed in the weights of single and twin born lambs (P > 0.01). Breed class affected lamb live weight and carcass composition with terminal lambs weighing heaviest and having greater muscle depth than all other breed classes investigated (P < 0.001). Lambs born to first parity dams were consistently lighter, regardless of time of weighing (P < 0.001), while dams lambing for the first time as ewe lambs produced lighter lambs than those lambing for the first time as hoggets (P < 0.001). Greater heterosis coefficients (i.e., >90% and ≤100%) resulted in heavier lambs at weaning compared with lambs with lower levels of heterosis coefficients (P < 0.001). A heterosis coefficient class <10% resulted in lambs with greater muscle depth while recombination loss of <10% increased ultrasound fat depth (P < 0.001). Results from this study highlight the impact of multiple animal level factors on lamb live weight and carcass composition which will enable more accurate bio-economic models and genetic evaluations going forward.
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Affiliation(s)
- Fiona Mary McGovern
- Teagasc, Animal & Grassland Research and Innovation Centre, Mellows Campus, Athenry, Co. Galway, Ireland
| | - Noirin McHugh
- Teagasc, Animal & Grassland Research and Innovation Centre, Fermoy, Co. Cork, Ireland
| | - Shauna Fitzmaurice
- Teagasc, Animal & Grassland Research and Innovation Centre, Fermoy, Co. Cork, Ireland
| | - Thierry Pabiou
- Sheep Ireland, Highfield House, Bandon, Co. Cork, Ireland
| | | | - Eamon Wall
- Sheep Ireland, Highfield House, Bandon, Co. Cork, Ireland
| | - Nicola Fetherstone
- Teagasc, Animal & Grassland Research and Innovation Centre, Mellows Campus, Athenry, Co. Galway, Ireland
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Pool KR, Rickard JP, de Graaf SP. Overcoming neuroendocrine and metabolic barriers to puberty: the role of melatonin in advancing puberty in ewe lambs. Domest Anim Endocrinol 2020; 72:106457. [PMID: 32361422 DOI: 10.1016/j.domaniend.2020.106457] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 01/07/2020] [Accepted: 02/19/2020] [Indexed: 02/05/2023]
Abstract
Pubertal onset in the ewe is subject to a multitude of physiological and environmental constraints. As seasonal breeders, sheep rely on decreasing photoperiod to enter puberty and the subsequent breeding periods, hindering production. The initiation of puberty defines the reproductive yield of the ewe, and as such is a critical factor influencing production outcomes. Currently, the misconception that ovine puberty is reliant on age results in ewes being bred at over a year old, leading to a substantial unproductive period between birth and first conception. As such, transcending pubertal barriers to allow for earlier initiation of reproductive competency has significant commercial merit. The primary candidate to achieve this is the neurohormone melatonin, a key factor that naturally signals photoperiodic change that facilitates seasonal remodeling of the ovine hypothalamic-hypophyseal-gonadal axis. Despite being known to modulate reproductive seasonality in both the mature ewe and ram, the ability of melatonin to advance ewe puberty remains underutilized in industry. To optimize melatonin application and shape perceptions of breeding ewe lambs, a greater understanding of pubertal impediments and the natural role of melatonin is warranted. This review examines the physiological role and applications of melatonin to advance ewe puberty, and how this may act in conjunction with other physiological and metabolic cues.
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Affiliation(s)
- K R Pool
- The University of Sydney, Faculty of Science, School of Life and Environmental Sciences, Sydney, NSW 2006, Australia.
| | - J P Rickard
- The University of Sydney, Faculty of Science, School of Life and Environmental Sciences, Sydney, NSW 2006, Australia
| | - S P de Graaf
- The University of Sydney, Faculty of Science, School of Life and Environmental Sciences, Sydney, NSW 2006, Australia
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Vallée E, Heuer C, Collins-Emerson JM, Benschop J, Ridler AL, Wilson PR. Effects of natural infection by L. borgpetersenii serovar Hardjo type Hardjo-bovis, L. interrogans serovar Pomona and leptospiral vaccination on sheep reproduction. Theriogenology 2018; 114:126-135. [PMID: 29609182 DOI: 10.1016/j.theriogenology.2018.03.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 02/23/2018] [Accepted: 03/16/2018] [Indexed: 10/17/2022]
Abstract
Most New Zealand sheep flocks are seropositive to Leptospira serovars Hardjo and/or Pomona, yet vaccination is rare. This study evaluated the impact of exposure to these serovars and of vaccination, on primiparous one- (P1) and two-year-old (P2) sheep reproduction outcomes. The study was designed as a split-flock vaccination trial, with a third of the animals vaccinated starting at one month of age. Reproduction outcomes were the proportion of bred P1 (7 months old) and as P2 (19 months old) scanned pregnant, the proportion of pregnant ewes rearing a lamb to tail docking and the proportion of docked lambs that were weaned. Odds ratios and their 95% confidence intervals were calculated to compare reproductive performance between vaccinated and control sheep, and within the control group, between seropositive and seronegative sheep. Odds ratios (OR) were also calculated to assess the relationship between vaccination and loss to follow-up. There was no difference in pregnancy and docking rates between vaccinated and control sheep, or between seropositive and seronegative sheep. P1 with a Hardjo titre ≥1536 were significantly less likely (OR = 0.41, 95%CI = 0.19-0.93) to keep a lamb between docking and weaning than P1 with both Hardjo and Pomona titres <1536, for an observed difference in weaning rate of up to 22.6% points on one farm. A reduction of weaning rates in 2-tooths seropositive for Pomona alone and both Hardjo and Pomona was observed but this was non-significant, possibly because of a lack of power. No difference in weaning rate was observed between vaccinated and control P1 or P2. On one farm vaccinated P1 were less likely to be lost to follow-up (OR = 0.27, 95% CI 0.08 to 0.95) between breeding and weaning. Comparing reproductive performance of vaccinated and control sheep revealed no significant difference. However, comparing exposed and non-exposed ewes revealed a possible adverse effect of Leptospira on weaning rates. This suggests that a full vaccination program may result in an improvement of reproductive outcomes, possibly by providing herd immunity.
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Affiliation(s)
- Emilie Vallée
- School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand; Epicentre, School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
| | - Cord Heuer
- Epicentre, School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
| | - Julie M Collins-Emerson
- (m)EpiLab, Hopkirk Research Institute, School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
| | - Jackie Benschop
- (m)EpiLab, Hopkirk Research Institute, School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
| | - Anne L Ridler
- School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
| | - Peter R Wilson
- School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
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Reduced ovulation rate, failure to be mated and fertilization failure/embryo loss are the underlying causes of poor reproductive performance in juvenile ewes. Anim Reprod Sci 2016; 167:125-32. [DOI: 10.1016/j.anireprosci.2016.02.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/17/2015] [Accepted: 02/16/2016] [Indexed: 11/18/2022]
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12
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Morris ST, Kenyon PR. Intensive sheep and beef production from pasture--a New Zealand perspective of concerns, opportunities and challenges. Meat Sci 2014; 98:330-5. [PMID: 24998778 DOI: 10.1016/j.meatsci.2014.06.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 06/12/2014] [Indexed: 11/25/2022]
Abstract
This paper details current production trends for sheep and beef cattle production in New Zealand and gives some insight into the opportunities for improvement based on New Zealand research at Massey University. Further it outlines some of the challenges the industries face in the near future. The New Zealand climate favours pasture growth and this is the key to sheep and beef cattle production with over 95% of the diet being grazed pasture or crop. Exports are the focus of the industry with 95% of sheep meat and wool, and 80% of beef exported. There have been considerable gains in production over the last 20 years but there still remains a huge opportunity for further intensification through breeding sheep at an earlier age, increasing the weight of lambs weaned per ewe per year and improving beef production systems. These improvements need to occur within a framework of minimal environmental footprint and produce products that are in demand in the high end international markets.
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Affiliation(s)
- S T Morris
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private bag 11222, Palmerston North 4410, New Zealand.
| | - P R Kenyon
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private bag 11222, Palmerston North 4410, New Zealand
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Abstract
Pre-natal and early post-natal ovarian development has become a field of increasing importance over recent years. The full effects of perturbations of ovarian development on adult fertility, through environmental changes or genetic anomalies, are only now being truly appreciated. Mitigation of these perturbations requires an understanding of the processes involved in the development of the ovary. Herein, we review some recent findings from mice, sheep, and cattle on the key events involved in ovarian development. We discuss the key process of germ cell migration, ovigerous cord formation, meiosis, and follicle formation and activation. We also review the key contributions of mesonephric cells to ovarian development and propose roles for these cells. Finally, we discuss polycystic ovary syndrome, premature ovarian failure, and pre-natal undernutrition; three key areas in which perturbations to ovarian development appear to have major effects on post-natal fertility.
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Affiliation(s)
- Peter Smith
- AgResearch InvermayPuddle Alley, Mosgiel 9053, New ZealandDepartment of AnatomyUniversity of Otago, Dunedin 9054, New ZealandDepartment of Anatomy and Developmental BiologyMonash University, Clayton, Victoria 3800, AustraliaRobinson Research InstituteDiscipline of Obstetrics and Gynaecology, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia 5005, AustraliaAgResearch InvermayPuddle Alley, Mosgiel 9053, New ZealandDepartment of AnatomyUniversity of Otago, Dunedin 9054, New ZealandDepartment of Anatomy and Developmental BiologyMonash University, Clayton, Victoria 3800, AustraliaRobinson Research InstituteDiscipline of Obstetrics and Gynaecology, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Dagmar Wilhelm
- AgResearch InvermayPuddle Alley, Mosgiel 9053, New ZealandDepartment of AnatomyUniversity of Otago, Dunedin 9054, New ZealandDepartment of Anatomy and Developmental BiologyMonash University, Clayton, Victoria 3800, AustraliaRobinson Research InstituteDiscipline of Obstetrics and Gynaecology, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Raymond J Rodgers
- AgResearch InvermayPuddle Alley, Mosgiel 9053, New ZealandDepartment of AnatomyUniversity of Otago, Dunedin 9054, New ZealandDepartment of Anatomy and Developmental BiologyMonash University, Clayton, Victoria 3800, AustraliaRobinson Research InstituteDiscipline of Obstetrics and Gynaecology, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia 5005, Australia
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Kenyon PR, Morris ST, West DM. Proportion of rams and the condition of ewe lambs at joining influences their breeding performance. ANIMAL PRODUCTION SCIENCE 2010. [DOI: 10.1071/an09178] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The aim of the present study was to examine the effects of ram : ewe lamb ratio and condition score on the reproductive performance of ewe lambs. In the 2007 study, ewe lambs were bred with rams, at ram : ewe lamb ratios of 1 : 30, 1 : 50, 1 : 75 or 1 : 100. In the 2008 study, ewe lambs were bred at ratios of 1 : 31, 1 : 50, 1 : 75 or 1 : 100. Ewe lambs were bred over two 17-day periods. In both studies, ewe lambs bred in the first 17 days of breeding only were heavier (P < 0.05) than those bred in the second 17-day period only, and those ewe lambs diagnosed as twin-bearing were heavier (P < 0.05) than their single-bearing counterparts. Ewe lambs with a condition score of 2.5 or greater were more likely (P < 0.05) to be bred, and be pregnant, in the first 17 days of breeding than those of condition score 1.5 or 2.0. Over the entire 34-day breeding period, ewe lambs with a condition score of 2.5 or greater had higher (P < 0.05) pregnancy rates than those with a condition score of 2.0, which in turn had higher rates than those of 1.5. In the 2007 study, after 34 days of breeding, there were no differences (P > 0.05) in pregnancy rates among the different ram : ewe lamb ratios. While in the 2008 study, pregnancy rates after 34 days were greater (P < 0.05) in the 1 : 50 compared with both the 1 : 75 and 1 : 100 treatments. Pregnancy rates of 1 : 31 ewe lambs were greater (P < 0.05) than those of 1 : 75 ewe lambs. In the 2007 study, pregnancy rates of ewe lambs to the first 17 days of breeding were greater (P < 0.05) for those bred at a ratio of 1 : 75 than for those bred at 1 : 50, and tended to be greater (P = 0.08) than for those bred at 1 : 100. In addition, those bred at a ratio of 1 : 30 tended to have higher pregnancy rates (P = 0.07) than those bred at 1 : 50. While in the 2008 study, pregnancy rates to the first 17 days of breeding were greatest (P < 0.05) in the 1 : 31 and 1 : 50 treatments groups. In conclusion, the results of the present study indicate that achieving greater liveweights and higher condition scores of ewe lambs at breeding will increase the proportion pregnant, especially early in the breeding period. The data also suggest, in combination with the results of previous research, that farmers should consider utilising ram : ewe lamb ratios lower than 1 : 100, although further studies are warranted.
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Mulvaney FJ, Morris ST, Kenyon PR, Morel PCH, West DM. Effect of nutrition pre-breeding and during pregnancy on breeding performance of ewe lambs. ANIMAL PRODUCTION SCIENCE 2010. [DOI: 10.1071/an10040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The objective of the present studies was to investigate the effect of differing nutritional levels before breeding and during the pregnancy period on the breeding activity, conception rate (proportion pregnant/ewe lambs bred), pregnancy rate (proportion pregnant/ewe lambs joined with the ram) and the number of fetuses identified at pregnancy diagnosis. In Study 1, ewe lambs were allocated to either ‘medium’ or ‘ad lib’ levels of herbage from 4 days before the start of the breeding period (P –4) to P64. In Study 2, four different pre-breeding nutritional groups (‘maintenance’, ‘medium’, ‘medium/ad lib’ and ‘ad lib’) were utilised from P –17 until P5. The ‘medium/ad lib’ group involved a nutritional switch from the ‘medium’ to the ‘ad lib’ group at P –4 and remained in the ‘ad lib’ until P5. At P5, all ewe lambs that were identified as bred (crayon-marked by ram) were allocated to either ‘medium’ or ‘ad lib’ levels of nutrition until P122. In Study 1, more (P < 0.05) ewe lambs were bred, identified as pregnant at P64 and more fetuses identified at P64 in the ‘ad lib’ group compared with the ‘medium’ group. In Study 2, fewer (P < 0.05) ‘maintenance’ pre-breeding group ewe lambs were bred over the 5-day breeding period compared with the other pre-breeding groups but the proportion of the ewe lambs pregnant at P53 did not differ (P > 0.05). In addition, more (P < 0.05) fetuses were identified at pregnancy diagnosis in the ‘ad lib’ pre-breeding group compared with all other pre-breeding groups. Post-breeding nutrition did not affect (P > 0.05) the proportion of ewe lambs displaying oestrus post-breeding, pregnancy rate or the number of fetuses identified at pregnancy diagnosis per ewe lamb present. This indicates that New Zealand pastoral farmers should aim to allow ad libitum levels of nutrition immediately before the start of the breeding period to pregnancy diagnosis to maximise the number of fetuses at pregnancy diagnosis.
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Kenyon PR, Smith SL, Morel PCH, Morris ST, West DM. The effect of the maturity and prior breeding activity of rams and body condition score of ewe hoggets on the reproductive performance of ewe hoggets. N Z Vet J 2009; 57:290-4. [PMID: 19802043 DOI: 10.1080/00480169.2009.58623] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To determine the effect of age and prior use of mature rams at a given ram-to-ewe ratio, and the effect of body condition on breeding performance and pregnancy rate of ewe hoggets. METHODS Ewe hoggets (n=733) aged 7-8 months were weighed and their body condition scored, then randomly assigned to one of three treatment groups (Day 0) and joined with either four two-tooth rams (20 months of age) not used previously (n=244; Two-tooth), four mixed-aged mature rams that had not been used earlier in the season (n=244; Mature-fresh), or four mixed-aged mature rams that had been used with mature ewes immediately prior to joining with hoggets (n=245; Mature-used). The breeding period was 34 days. Ewe hoggets were identified as having been marked during the first 17 days only, during both 17-day periods, during the second 17 days only, or not marked. Hoggets were re-weighed on Day 34, and pregnancy status determined using ultrasound on Day 92. The breeding soundness of the rams was assessed on Days -34 and -1. RESULTS Semen samples obtained from the rams did not differ significantly in any of the parameters measured (p>0.05). Ewe hoggets joined with Mature-fresh rams were less likely (p<0.05) to be marked in the second 17 days of breeding only than those joined with either Two-tooth or Mature-used rams. No other breeding parameters were affected by breeding group (p>0.05). Hoggets marked in the first 17 days only were heavier (p<0.05) at Day 0 than those marked in the second 17 days only or not marked. Hoggets diagnosed as twin-bearing were heavier (p<0.05) than non-pregnant or single-bearing hoggets. Those hoggets marked in the first 17 days only had a greater (p<0.05) body condition score (BCS) than those marked in the second 17 days only or not marked at all. These differences were no longer apparent after correction for liveweight (LW).Correction for LW at Day 0 or change in LW during the breeding period did not affect the results for breeding performance. CONCLUSIONS Under the conditions of this study, two-tooth rams and mature rams that had been used previously were just as suitable as mature rams that had not been used previously for breeding with ewe hoggets. Further studies are warranted to verify this result. The re-use of rams without reducing breeding performance would reduce breeding costs and may make breeding hoggets a more viable option for farmers. The BCS of ewe hoggets affected breeding performance, and can thus be used to identify those animals most suitable for breeding.
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Affiliation(s)
- P R Kenyon
- Sheep Research Group, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
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Tabbaa MJ, Al-Atiyat R. Breeding objectives, selection criteria and factors influencing them for goat breeds in Jordan. Small Rumin Res 2009. [DOI: 10.1016/j.smallrumres.2009.03.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Musonda K, Barry T, McWilliam E, Lopez-Villalobos N, Pomroy W. Grazing willow (Salix spp.) fodder blocks for increased reproductive rates and internal parasite control in mated hoggets. Anim Feed Sci Technol 2009. [DOI: 10.1016/j.anifeedsci.2008.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Stafford KJ, Gregory NG. Implications of intensification of pastoral animal production on animal welfare. N Z Vet J 2008; 56:274-80. [DOI: 10.1080/00480169.2008.36847] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kenyon P, Proctor L, Morel P, Morris S, West D. The effect of breeding ewe lambs on subsequent two-year-old ewe performance. Livest Sci 2008. [DOI: 10.1016/j.livsci.2007.07.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kenyon PR, Morel PCH, Morris ST, Burnham DL, West DM. Effect of the ratio of teaser rams used prior to breeding on the reproductive performance of ewe hoggets. N Z Vet J 2007; 55:342-5. [DOI: 10.1080/00480169.2007.36791] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kenyon PR, Morel PCH, Morris ST, West DM. Effect of the age of rams on reproductive performance of ewe hoggets. N Z Vet J 2007; 55:184-7. [PMID: 17676083 DOI: 10.1080/00480169.2007.36765] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To determine the effect of the age of rams, used at a standardised ram-to-ewe ratio, on the breeding performance and pregnancy rate of ewe hoggets. METHODS Ewe hoggets ((1/2) Romney x (1/4) Texel x (1/4) Finnish Landrace; n=582) aged 7-8 months were exposed to nine two-tooth, harnessed, vasectomised teaser rams for a period of 17 days (Days 1-17). The ewe hoggets were then weighed and randomly assigned to one of three treatment groups (on Day 18) and joined with either four ram hoggets not used previously (n=194), four two-tooth rams not used previously (n=196), or four mixed-age mature rams (n=192) that had been used previously to mate mature ewes immediately before breeding with the ewe hoggets. The breeding period was 34 days. Ewe hoggets were identified as having been mated during the first 17 days only, during both 17-day periods, during the second 17 days only, or not mated. All ewe hoggets were scanned for pregnancy using ultrasound, 54 days after the end of the breeding period. RESULTS Liveweights of ewe hoggets did not differ between treatment groups. More ewe hoggets were mated by the mature rams in the first 17 days than by either ram hoggets or two-tooth rams (p<0.05). However, more of the ewe hoggets mated by mature rams returned to service (failed to conceive), and the percentage of ewe hoggets bred in the first 17 days only or pregnant from a service in the first 17 days did not differ significantly between groups. Fewer of the ewe hoggets joined with ram hoggets were diagnosed as pregnant after 34 days of breeding compared with those joined with either two-tooth or mature rams (p<0.05), as more ewe hoggets failed to be mated at all by ram hoggets compared with those joined with mature rams (p<0.05). There was also a tendency for more ewe hoggets joined with ram hoggets not to be mated at all compared with those joined with two-tooth rams (p=0.07). CONCLUSIONS Two-tooth rams previously unused and mature rams previously used for mating were a better option than unused ram hoggets to maximise the pregnancy rate of ewe hoggets to a 34-day breeding period. However, further work is required as it was unclear why lower conception rates were observed in ewe hoggets joined with mature rams which had been used previously. As a result, the advantage of using mature rams may have been underestimated.
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Affiliation(s)
- P R Kenyon
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
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Fogarty NM, Ingham VM, Gilmour AR, Afolayan RA, Cummins LJ, Edwards JEH, Gaunt GM. Genetic evaluation of crossbred lamb production. 5. Age of puberty and lambing performance of yearling crossbred ewes. ACTA ACUST UNITED AC 2007. [DOI: 10.1071/ar06401] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The age and liveweight at puberty were evaluated in 2155 crossbred ewe lambs at 2 sites over 3 years. A separate dataset examined the lambing performance of 1177 crossbred ewe lambs that were joined naturally at ~7 months of age at 2 sites over 3 years and also their lambing performances in the subsequent 2 years. The ewe lambs were the progeny of Merino dams and sires from several breeds including Border Leicester, East Friesian, Finnsheep, Coopworth, White Suffolk, Corriedale, and Booroola Leicester. Overall, 85% of the ewe lambs reached puberty (detected by teasers) in their first autumn at an average age of 248 days and liveweight of 42 kg. There was significant variation in age and weight at puberty (P < 0.01) among the site and year cohorts of ewes. Sire breed was significant for weight (P < 0.01) but not age at puberty. Of the crossbred ewe lambs joined at 7 months of age, 54% lambed with an average litter size of 1.31 and 49% of lambs were weaned from the ewes joined. There was a significant site effect for all reproduction traits (P < 0.01), with the higher performance at one site associated with higher liveweight at joining. Maternal sire breed was significant for all reproduction traits (P < 0.01) and there was considerable variation between sires within sire breeds. Ewes that reared lambs in their first year weaned 12% more lambs per year in their second and third years compared with ewes that failed to lamb or rear any lambs at 1 year of age. The results demonstrate that lamb weaning rates of 90% or more can be achieved from crossbred ewe lambs with optimal genetics and management. The opportunities for improving productivity by joining crossbred ewe lambs and the selection and management considerations required for successful joinings and lambings are reviewed and discussed.
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Kenyon PR, Morel PCH, Morris ST, Burnham DL, West DM. The effect of length of use of teaser rams prior to mating and individual liveweight on the reproductive performance of ewe hoggets. N Z Vet J 2006; 54:91-5. [PMID: 16596161 DOI: 10.1080/00480169.2006.36618] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To determine the effects of liveweight (LW) and duration of teasing with vasectomised rams prior to breeding on both the mating performance and pregnancy rate of ewe hoggets. METHODS Five hundred and forty-six (1/2) Romney x (1/4) Texel x (1/4) Finnish Landrace ewe hoggets were weighed and randomly assigned to one of three treatment groups: either exposed to five harnessed vasectomised (teaser) rams for 17 days prior to the breeding period (T17; n =181); exposed to five harnessed teaser rams for 8 days prior to the breeding period (T8; n = 184); or not exposed to teasers (unteased; n = 181). Harnessed entire rams of the same breed were then introduced for the duration of two oestrous cycles. Using crayon marks, hoggets were identified as having been mated in the first 5 days, Days 6-10, Days 11-17, during the first 17 days only, during both 17-day periods, during the second 17 days only, or not mated. All hoggets that were mated were scanned for pregnancy, using ultrasound, 48 days after the end of the breeding period, and identified as being either non-pregnant, or as singleton- or twin-bearing. RESULTS Hoggets mated in the second 17-day period only were significantly lighter than those mated in either the first 17-day period only (p < 0.001), or in both the first and second 17-day periods (p < 0.02). At Day 1, twin-bearing hoggets were heavier than singleton-bearing hoggets (p < 0.001) and tended to be heavier (p = 0.06) than non-pregnant hoggets. At Day 18, twin-bearing hoggets were heavier than non-pregnant (p = 0.01) and singleton-bearing (p < 0.01) hoggets. A lesser proportion (p < 0.001) of unteased hoggets was mated in the first 17-day period only, compared to T17 hoggets. Conversely, a greater proportion of unteased hoggets was mated in the second 17-day period only, compared to either T8 (p < 0.01) or T17 (p < 0.001) hoggets. A lesser proportion of unteased hoggets was mated in the first 17 days of breeding, regardless of whether they returned to oestrus or not, in comparison to either T8 (p = 0.001) or T17 (p < 0.001) hoggets. Of those mated in the first 17 days of the breeding period, T8 hoggets were less likely (p < 0.05) to be mated in the first 5 days of that period but more likely to be mated in the last 7 days, compared to unteased and T17 hoggets. T17 hoggets had higher pregnancy rates to the first 17 days of breeding compared with either unteased (p = 0.01) or T8 hoggets (p = 0.06), and were more likely (p < 0.05) to be twin-bearing. In addition, the scanning percentage of T17 hoggets was higher than either unteased or T8 hoggets (p < 0.05). CONCLUSIONS Heavier hoggets at breeding are more likely to be mated during the first 17 days of breeding and to be twin-bearing. While teasing for just 8 days increased the numbers mated in the first 17 days of breeding it did not increase the numbers of hoggets pregnant to that period. In contrast, teasing for 17 days did increase the numbers pregnant to the first 17 days of breeding and also increased the overall scanning percentage. It is recommended that farmers use a 17-day period of teasing before the breeding of ewe hoggets.
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Affiliation(s)
- P R Kenyon
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
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Kenyon PR, Morel PCH, Morris ST, West DM. The effect of individual liveweight and use of teaser rams prior to mating on the reproductive performance of ewe hoggets. N Z Vet J 2005; 53:340-3. [PMID: 16220128 DOI: 10.1080/00480169.2005.36571] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To determine the effects of liveweight (LW) and use of teaser rams prior to mating on both the mating performance and pregnancy rate of ewe hoggets. METHODS Romney hoggets (n=841) were weighed and randomly assigned to one of two treatment groups; either exposed to seven harnessed, vasectomised (teaser) rams for 17 days prior to the breeding period (n=283); or not exposed to teaser rams (unteased, n=558). Harnessed Perendale rams were then introduced for two oestrous cycles. Using crayon marks, hoggets were identified as having been mated during the first 17 days only, during the second 17 days only, during both periods, or not mated. All mated hoggets were then scanned for pregnancy using ultrasound, 48 days after the end of the breeding period, and identified as being either non-pregnant, or as single-, twin or triplet-bearing. RESULTS Hoggets mated in either the first 17 days only or in both the first and second 17-day periods were heavier than those mated in the second period only (p<0.001). Those mated in the first or second 17-day period only, and those mated in both periods were all heavier prior to mating than those not mated at all (p<0.001). Twin-bearing hoggets were heavier than both their single-bearing and non-pregnant counterparts (p<0.001). A greater proportion of the teased hoggets were mated in the first 17 days only compared with unteased hoggets (62.6 vs 32.1%; p<0.001). In contrast, more of the unteased hoggets were marked in the second 17-day period only (p<0.001). A greater proportion of mated, unteased hoggets were found to be non-pregnant in comparison to their teased counterparts (17.8 vs 11.2%; p=0.02). CONCLUSIONS Heavier hoggets at breeding were more likely to be mated in the first 17 days of the breeding period and more likely to be twin-bearing. Use of teaser rams for 17 days prior to the breeding period increased the proportion of hoggets mated in the first 17 days, increased conception rates, and thus increased the proportion of pregnant hoggets. These results indicate that farmers should utilise teasers for 17 days prior to commencement of the breeding period and avoid mating hoggets that weigh below 36 kg.
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Affiliation(s)
- P R Kenyon
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
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