In pigs, a mutation on the RyR1 calcic canal gene is the cause of serious metabolic upsets leading to the development of a syndrome of malignant hyperthermia caused by perturbations in the flow of calcium ions through the membranes of the muscle cells.
After slaughter, the post-mortem pH of the meat from those pigs said to be “stress-sensitive” decreases too rapidly, leading to lower quality meat.
Scrapie in sheep, also called staggers, is a prion-based animal disease, belonging to the group of transmissible spongiform encephalopathies that attack small ruminants. The disease is characterised by the appearance of behavioural problems linked to an attack on the central nervous system and it is always terminal. Scrapie is not a genetic illness, but is caused by Non-Conventional Transmissible Agents (NCTA) also known as “pathogenic prions”.
The gene, known as the PrP gene, is a coding gene for the PrP protein prion that is the causal agent or at least an agent associated with the development of scrapie. This PrP gene has an influence on the pre-disposition of sheep to contract scrapie if they are exposed to the infection.
In sheep, the genotype at the level of the 136, 154 and 171 codons of the PrP gene determines their potential sensitivity or resistance to the disease.
Typing the PrP gene may be carried out on sheep of all ages and is thus a valuable tool in selecting sheep having a natural resistance to scrapie.
The bovine “culard” characteristic is a generalised hypertrophy resulting from hyperplasia of the muscle fibres.
This characteristic is sought after in meat races: for the same diet, the “culard” animals are not significantly heavier than mixed beasts of the same race, but they have more muscle and less fat. This means that on slaughter they have a greater yield. Furthermore, meat from “culard” animals has less fat and is more tender.
The “culard” phenotype is a result of mutations occurring in the myostatin genetic sequence.