Maternal Lambing Traits

Summary

Reproductive rates (i.e. fertility and multiple birth rates) are rapidly improving within the sheep industry. The number of lambs weaned is a crucial profit driver and producers are placing more emphasis on the importance of lamb survival.

To date the impact that maternal traits have on subsequent production traits in the progeny is not clearly known. The lack of a standardised system for recording maternal traits has also been noted. This project has supplied a database that has been collated and standardised as much as is practical given the diversity of individual criteria. The database includes information from eight seed-stock producers representing five breeds and two composite breeds that are used in the sheep wool and meat industry.

The data provides some information on the maternal ability of individual ewes and may be used to determine the impact that maternal traits can have on important production traits in the offspring such as lamb survival and growth rate. Additionally, the database will be used to provide an estimate of the heritability of maternal behaviour in ewes.

Seed-stock producers supplied a diverse range of maternal traits they considered important to their system. Since there is no current standardised system for recording maternal traits the breeders have developed their own subjective recording systems through consultation with other breeders, researchers and from their own anecdotal experiences. Several breeders have been recording maternal traits for many years and other breeders have commenced recording traits only recently. All data has been supplied from breeders who are long term users of LAMBPLAN or MGS for breeding selection. Pedigree information is available on all animals within their studs and information on the animals in this database would also be recorded in the LAMBPLAN or MGS database, therefore providing reliable linkages between both databases for genetic analysis. A total of 7,370 individual ewe records have been recorded in this database. Information was supplied for the following traits: ewe flight distance, maternal score, vocal score, udder score, birth coat, lamb ease and TOBY (evasive to humans) scores.

Although the scope of this project was to collate and supply the database to LAMBPLAN, it should be noted that that comments derived from anecdotal evidence supplied by breeders might impact on the interpretation of maternal trait assessments. These comments are listed in the discussion section of the main report.

There appears to be a need within the sheep seed-stock industry for a standardised recording system for maternal traits. The variation in criteria for assessment, and breeders comments as shown in this report, indicates that factors such as climate, breed, paddock size, and assessment procedure all contribute to variation in maternal traits and therefore lamb survival. These factors would need to be taken into account when considering a standardised assessment procedure if it is shown after analysis, that maternal traits have a significant impact on production and heritability can be accurately estimated.