Abstract
Breeding hoggets (ewe lambs aged four to 16 months) at 8 to 9 months of age has a number of potential benefits, including increased lamb production and profitability. However, the majority of hoggets in New Zealand are not bred due to producer concerns regarding their variable reproductive success and increased feed demand. Simulation modelling was used to quantify effects of hogget breeding on sheep numbers, lamb production, sheep feed demand, and sheep enterprise cash operating surplus (COS) compared with a flock not breeding hoggets. Hogget weaning rate (HWR) was modelled at 0%, 60%, 80%, and 100% and combined with mature ewe flock weaning rates (FWR) of 132% and 150%, while maintaining total annual sheep feed demand. For each FWR, increased HWR reduced total sheep numbers, increased the proportion of sheep feed demand for lamb production, increased total numbers of lambs weaned, and increased COS. Therefore, achieving even a relatively low HWR of 60% can improve sheep enterprise profitability for a given FWR. However, COS was lower with FWR = 132% and HWR = 100% than with FWR = 150% and HWR = 0%. The results indicate farmers who do not currently breed their hoggets may wish to improve their FWR before considering HWRs.
Highlights
To maintain the overall total annual sheep feed demand with flock weaning rates (FWR) increased to 150%, there were fewer ewes in the flock
Hogget breeding always increased sheep enterprise cash operating surplus (COS) with the modelled Hogget weaning rate (HWR) of 60% and higher compared with a flock not breeding hoggets
Hogget breeding increased profit even with a relatively low HWR for a given FWR. These increases in COS were achieved while maintaining a constant total annual sheep feed demand
Summary
Hoggets (ewe lambs aged four to 16 months) have the potential to be successfully bred at 8 to 9 months of age and in New Zealand 32% of hoggets were presented for breeding in 2019 [1].Stated production benefits from breeding hoggets include: (1) increased utilisation of pasture in spring,(2) increased numbers of lambs weaned, (3) more lambs available for sale providing additional income,(4) an additional selection tool for ewe replacements, (5) increased selection pressure for replacements if replacements are selected from those born to hoggets, (6) reduced generation interval if replacements are selected from those born to hoggets, and (7) reduced greenhouse gas emissions intensity on a per kg of product basis [2,3,4,5,6,7,8,9,10,11,12]. As indicated by the majority of New Zealand sheep farmers not breeding hoggets, there are producer concerns These include: (1) variable hogget reproductive success, (2) increased total farm feed demand unless changes are made to numbers of other stock classes, (3) greater live weight targets at 8 to 9 months of age, (4) potential for negative consequences on future live weight and productivity, (5) potential lighter live weights and poorer survival to weaning of hogget progeny, (6) potential for increased expenses, and (7) the potential of increasing the mortality rates of hoggets [3,7,8,10,11,12,13,14]. The second objective of the current study was to quantify the profitability of scenarios with combinations of varying hogget and mature weaning rates with consistent total annual sheep feed demand between scenarios
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