These considerations arise from my studies and experiences and from the teachers I quote: Bertrand Vissac (B.V.) Keith Gregory (K.G.) Héctor Molinuevo (H.M.) and Fernando Lagos (F.L.).
Genetics is a science that developed rapidly in just half a century creating formidable instruments for gene manipulation and prediction of heredity.
Except for exceptions, the characters are the result of thousands of “genes”. Little that the few that have been detected are affected and when they do they will be owned by big companies as it has happened in vegetables, birds and pigs.
In some easy-to-measure characters on very large populations (B.V.) under controlled environmental conditions, predictions have produced astounding results. Such is the case of dairy, avian and porcine production.
In beef cattle, when a character is poorly inherited, either because it is heavily influenced by the environment or because its measurement is imprecise, the DEP (Expected Progeny Differences) are inoperative and should be interpreted as PED (Precarious Expressions of Desires) . However, they are an excellent argument for commercial promotion with scientific support.
Millennia of natural selection adapted the existing biotypes to conditions as different as the tropics, semiarid and snow. Selecting in the same environment not only allows to better evaluate the adaptation characters, but also takes advantage of changes caused by the same, which are inheritable. This different mode of inheritance “Epigenetic” has been recently demonstrated.
Improvement is an art prior to genetics, is to find in the middle of a great variability, the most outstanding individuals, by appropriate control of the characters of greater economic value under the conditions of each production system (environmental and commercial) .
With this art were created all the pure breeds existing in Europe, those of threefold purpose that led to milk; In the south the muscle was sought for the work of the earth (B.V.); In the islands we sought in grease, energy for the industrial revolution (K.G.). Perfection in that art was achieved with pure blood for speed.
No race has an optimal level for all characters and intra-race selection operates barely and when the variability is exhausted or missing (H.M.).
From the 50’s, the cross revolution allowed the combination of complementary characters (B.V.), and great variability to enhance a much more efficient selection. Starting from an initial composition, independent characters (size, muscle, hump, etc.) can be accentuated quickly or they can become compromises (F.L.) with those that are negatively related (muscle and fat, etc.). It is not impossible but very difficult to find individuals who escape that relationship.
With immediate results and the aid of fairly vigorous hybrid vigor (K.G.) successful synthetic breeds were created here: Brangus, Bradford and Limangus. Finally, the question was asked by E. Olivera, the founder of the SRA: “Why are there no Argentine races?”
The crosses recommended to take advantage of the hybrid vigor, failed in the country, not only due to management complications and genetic unevenness, but also due to the devaluation of the liquid brand.
They also helped to change types that took a century to shrink and became larger in a decade. “No New Type !, Friesian Type (K.G.)
Reproductive Manual: Maternal fertility is a threshold character strongly influenced by the environment, difficult to measure. A palliative to conserve it is to eliminate from the service of replacement those who do not have calves at the foot (if they were all there would be no cows in the country), and to improve it in the long term, it would be necessary to privilege the great mothers, And put on false teeth and get embryos. As parents of hut use only those of more than 5 services (H.M.). Too many bulls are left without legs in the middle of the game. It was not the case of Capicúa and Mariano, great trainers of the Limangus race that served in the field until the 20 years.
Sexual Precocity, independent of fertility, influenced by nutrition, is a character against nature (for protection of wild children), is very desirable for early service. It could be characterized with biweekly exams of sexual activity, with markers, or more easily with age at the very first delivery of a very early service.
The scrotal circumference from a threshold is debatable. I quote the case of the Limangus Ideal, CRB record (more than 4000 straws per month) without a C.E. Notorious Periodic measurements of the development of puberty would be more desirable than if they were related to that of females.
The Childbirth Facility is very difficult to measure because it is a threshold character that manifests itself almost exclusively in first years, which are very affected.