Two hundred and thirty-nine pigs reared at the Meat and Livestock Commission's Stotfold Pig Development Unit and derived from the four major breeding companies in the UK were slaughtered at 63 kg live weight in an experiment which examined the effect of genotype (Meat-line or White-line), pre-slaughter transport time (1 or 4 h) and lairage time (2 or 21 h) on carcass and meat quality. The pre-slaughter handling was chosen to simulate good commercial procedures and cover the range of transport and lairage times probably experienced by a large proportion of British slaughter pigs. Meatline pigs had higher killing-out proportions and heavier carcasses, with increased cross-sectional area of the m. longissimus dorsi. Backfat thickness was similar in the two genotypes. White-line pigs had heavier livers and produced meat which potentially had a lower incidence of PSE. Longer transport time increased live-weight loss. It reduced carcass yield in the White-line but not in the Meat-line pigs. Transport had no major effects on meat quality. Longer lairage, during which the pigs were fed in compliance with the law, resulted in reduced carcass yield but increased liver weight and allowed some repletion of liver glycogen. It also reduced ultimate pH values in the m. semimembranosus and m. adductor. There were no important or consistent differences in the way pigs of the two genotypes responded to pre-slaughter handling.

In this paper we consider mappings induced by matrix multiplication which are defined on lattices of matrices whose coordinates come from a fixed orthomodular lattice L (i.e. a lattice with an orthocomplementation denoted by ′ in which a ≦ b ⇒ a ∨ (a′ ∧ b) = b). will denote the set of all m × n matrices over L with partial order and lattice operations defined coordinatewise. For conformal matrices A and B the (i,j)th coordinate of the matrix product AB is defined to be (AB)ij = Vk(Aik ∧ BkJ). We assume familiarity with the notation and results of [1]. is an orthomodular lattice and the (lattice) centre of is defined as , where we say that A commutes with B and write . In § 1 it is shown that mappings from into characterized by right multiplication X → XP (P ∈ ) are residuated if and only if p ∈ ℘ (). (Similarly for left multiplication.) This result is used to show the existence of residuated pairs. Hence, in § 2 we are able to extend a result of Blyth [3] which relates invertible and cancellable matrices (see Theorem 3 and its corollaries). Finally, for right (left) multiplication mappings, characterizations are given in § 3 for closure operators, quantifiers, range closed mappings, and Sasaki projections.