The efficiency of determining the chemical composition of lamb carcasses

Abstract

A comparatively rapid method for estimating the chemical composition of mutton carcasses has been reported previously (Barton & Kirton, 1956 and a detailed description of the procedure has been given by Kirton & Barton (1958). The method involved the cutting of a frozen carcass down the back-bone. One side was then sliced and the slices, consisting of frozen flesh and bone, were ground (minced) in a commercial grinder (mincer). Samples were drawn from the thrice-ground material and these were analysed chemically. Treatment differences between groups of carcasses have been detected using this procedure, but hitherto it was not possible to study the magnitude of any errors inherent in the method. MATERIALS AND METHODSTwenty Southdown-Romney cross wether lambs which had been used in an investigation into the effects of cortisone and hecogenin on wool growth and live weight were available for carcass analyses. No differences of any importance due to the effects of the drugs were observed on live weight or in carcass composition of these lambs; hence they were suitable for the present study.At slaughter the animals had an average live weight of 78 lb. (range 63-5-93-8 lb.) and their hot carcass weight averaged 39-2 lb. with a range of 31-2-43-8 lb. Slaughtering and dressing followed commercial practice; thus each carcass was headless and the bones of the lower limbs from and including the metacarpals and metatarsals were removed. The kidneys were removed but the perirenal fat was left intact in the carcass. The carcasses were placed in a chiller overnight and then they were frozen and stored until required. Following approximately a year of storage the frozen carcasses averaging by then 36-6 lb. in weight were brought in twos and threes to the meat laboratory for analyses.These carcasses while still frozen were divided down the back-bone using a meat band-saw, then each side was cut into four parts, namely, leg, loin, rib cut, and fore. (a) Jointing of a sideAll jointing was done with a band-saw. A cut was made between the last thoracic and 1st lumbar vertebrae and the rib (usually the 13th) was followed out to the flank. The loin, including all perirenal fat, was removed from the posterior part of the carcass by cutting between the last lumbar and the 1st sacral vertebrae and continuing this cut at right angles to the back-bone through to the flank. The loin contained six or seven vertebrae. In cutting at right angles to the back-bone a small tip of the ilium was invariably severed and this became part of the loin. The part designated as the leg comprised the remainder of the posterior portion of the side and thus included the greater part of the pelvis.The rib cut, consisting of the 9th, 10th and 11th ribs, was removed from the anterior portion by cutting midway between the 8th and 9th ribs and midway between the 11th and 12th ribs. The cuts were made from the back-bone through to the flank, but because of the necessity of cutting midway between the ribs it was not always possible to commence the cut between the app...

A comparison between 15 ram breeds for export lamb production 1. Liveweights, body components, carcass measurements, and composition

“…They were then chopped up on a bandsaw into small pieces which were minced, bone and all, through a standard butcher's mincer using a cutting plate with 1-cm diameter holes. The minced material from each side was then minced twice more to achieve mixing and then sampled for chemical analysis as described by Kirton et al (1962). Duplicate subsamples were taken from each animal's sample for analysis of water, ether extract, ash, and dried, fat-free, ashfree residue (protein).…”

Palatability characteristics of crossbred lambs as related to individual southdown sires, slaughter age, and carcass fatness

“…The ether-extract of the left side of each carcass was determined on two 50 g samples per side (Kirton, Barton, and Rae 1962).…”

The nutrient composition of South African lamb (A2 grade)

“…The raw and cooked nutrient data of the three cuts was compared. The assumption, as confirmed by Kirton et al (1962), is that the composition of the two sides is similar.…”