Genetic and economic benefits of foreign sire contributions to a domestic sheep industry; including an Ireland-New Zealand case study

Abstract

Background Importation of foreign genetics is a widely used genetic improvement strategy. However, even if the foreign genetic merit is currently greater than the domestic genetic merit, differences in foreign and domestic trends mean that the long-term competitiveness of an importation strategy cannot be guaranteed. Gene flow models are used to quantify the impact that a specific subpopulation, such as foreign genetics, can have over time on the genetic or economic benefit of a domestic industry. Methods We used a deterministic recursive gene flow model to predict the commercial performance of lambs born across various subpopulations. Numerous breeding strategies were evaluated by varying market share, proportions of rams selected for mating, genetic trend, superiority of foreign genetics over domestic genetics and frequency of importation. Specifically, an Ireland-New Zealand case study was simulated to quantify the potential gain that could be made by using foreign sire contributions (New Zealand) in a domestic sheep industry (Ireland). Results Genetic and economic gains were generated from alternative breeding strategies. The ‘base scenario’ (i.e. representing the current industry) predicted an average genetic merit value of €2.51 for lambs born and an annualised cumulative benefit of €45 million (m) after 20 years. Maximum genetic (€9.45 for lambs born) and economic (annualised cumulative benefit of €180 m after 20 years) benefits were achieved by implementing the ‘PRO-intense-market scenario’ which involved shifting market share away from conservative domestic breeders and reducing the proportion of rams that were selected for mating by progressive domestic breeders from the top 40% to the top 20%, without the use of any foreign genetics. The ‘PROFOR scenario’, which considered the use of foreign and progressive domestic genetics, predicted an average genetic merit value of €7.37 for lambs born and an annualised cumulative benefit of €144 m, after 20 years. Conclusions Our results demonstrate that there is opportunity for a domestic industry to increase industry benefits without the use of foreign genetics but through an attempt to shift the market share away from conservative domestic breeders towards progressive domestic breeders. However, the importation and use of progressive foreign genetics may be an effective method to trigger a change in behaviour of conservative domestic breeders towards the use of progressive genetics.

The impact of maternal genetic merit and country of origin on ewe reproductive performance, lambing performance, and ewe survival

“…However, results from the current study deviated from expectation, in that high genetic merit ewes of Irish origin did not always outperform their low Irish counterparts, albeit differences were detected in the total number of lambs born and weaned. The establishment of the Irish national sheep breeding program has initiated commercial farmers within the Irish sheep industry to seek change as they attempt to increase production gains, with an estimated 13% of breeding rams sourced from progressive pedigree breeders ( Fetherstone et al, 2021 ). NZ has previously reported greater genetic gains relative to those achieved in Ireland ( Santos et al, 2015 ), which prompted the comparison of high maternal genetic merit animals from NZ and Ireland within the same production system.…”

“…Three genetic groups of ewes, balanced for breed and age, were established, containing 60 NZ ewes of high maternal genetic merit, 60 Irish ewes of high maternal genetic merit (High Irish), and 60 Irish ewes of low maternal genetic merit (Low Irish). A cohort of NZ animals selected based on the New Zealand Maternal Worth Index was imported to Ireland in 2013 and 2014 ahead of the commencement of this study with mating in October 2015; these animals represented those ranked within the top 40% across breed for maternal genetic merit ( Byrne et al, 2012 ) and were selected from six progressive flocks that achieved the equivalent genetic gain of €0.18 under the New Zealand Maternal Worth Index as previously discussed by Fetherstone et al (2021) . Irish ewes were selected based on their genetic merit at the time of entry into the study for the Irish maternal genetic index for sheep; i.e., the €uro-star Replacement index ( Bohan et al, 2019 ).…”

The impact of genetic merit on ewe performance and efficiency parameters

“…The superiority of high genetic merit ewes, in comparison to low genetic merit ewes, has previously been demonstrated across many reproductive, lambing, and lamb performance traits ( Lewis et al, 1996 ; Márquez et al, 2013 ; Fetherstone et al, 2021c ), and the potential benefits to industry from their strategic use have been discussed ( Fetherstone et al, 2021a ). However, to the authors’ knowledge, few studies, if any, have simultaneously recorded this variety of ewe performance and novel efficiency traits within a production system study in the past.…”