Abstract

In sheep, decreasing adipose or fat is desirable in prime lambs; however, adipose also has a role in the productive capacity of the maternal ewe. There are three main depots of adipose within the body of a live animal: sub-cutaneous, intermuscular and internal (or visceral). To understand if differences exist between animals in adipose deposition and partitioning, a study was undertaken using 37 New Zealand composite-breed maternal ewes, scanned using computed tomography on three occasions from nine through to 17 months of age. The images produced were processed to estimate the weight of subcutaneous, intermuscular and visceral adipose (along with lean and bone), with the weights then expressed as a percentage of total adipose to investigate partitioning. The raw average total body adipose remained proportionate across the three scans at approximately 32% of total empty body weight. The resulting data were analysed using a REML variance components analysis in Genstat. The repeatability of fat distribution across the three scans was high, ranging from 0.77 for proportion of intermuscular adipose through to 0.83 for proportion of subcutaneous adipose. The component Animal was significant for all traits indicating between animal variation in partitioning of adipose between the depots within individual animals. Cumulatively, these results demonstrate that there is variability in adipose deposition and partitioning in New Zealand sheep. If under genetic control, variability that could be exploited to optimise adipose to best meet the requirements of prime lamb production and maternal ewes.

Johnson, PL, WE Bain, P Johnstone, M Bixley, and K Knowler

Proceedings of the New Zealand Society of Animal Production, Volume 76, Adelaide, 122-125, 2016