Page 14 - April 2018

Pig Farm Perspective
The impacts of marbling on production traits and carcass composition
by Bruce the brainy pig
CURRENTLY in the race towards an antibiotic-free future, probiotics and fully understanding the pig stomach biome (col- lection of bacteria and how they work togeth- er) are the forefront to control the type and number of bacteria and to control nasty bugs that would ordi- narily cause disease.
Several studies have published genetic se- quencing of the gut bi- ome before and after weaning, and all stud- ies so far have shown a dramatic change in the type of bugs and number of bugs before and after.
The rush now is to find how we can ma- nipulate the good and the bad to our advan- tage to produce a wean- er pig with stable gut health.
So what are probiot- ics and how do we use them?
Probiotics are live whole bacteria or live modified bacteria that cannot cause disease in an animal.
The general idea is we deliberately
populate the gut with ‘healthy bugs’ so there is no food and no sites for attachment if any nasty bugs happen to pass through the body.
In addition, they can neutralise toxins in the intestinal tract, prevent the adhesion of patho- gens to the mucosal surface by competition, stimulate local immune defences and reduce the numbers of nasty bugs by competition.
In reality, some of these instances do oc- cur, however given the most commonly used organisms for probiot- ics are lactobacilli, we are provided with a dif- ferent option.
This kind of probi- otic works in a differ- ent way and lactobacilli produce lactic acid, which alters the pH of the gut, making an acid environment.
This acid environ- ment makes it very dif- ficult for bugs such as nasty strains of E. coli to establish.
So, delving into envi- ronmental control is an effective option in the future, and ideally our objective is to main-
tain the structure and function of the gut of the pig and enable it to digest, absorb and maintain a stable and effective immune sys- tem at all times.
Looking over the pad- dock fence, probiotics are taken to a com- pletely different level in cattle and horses, whereby if an animal is sick due to abnor- mal gut bugs, the stom- ach or colon contents can be collected from a healthy animal and tubed into the sick ani- mal.
This process is highly effective at altering the bug population in the gut and is called trans- faunation.
Studies have found cows with displaced stomachs that received bugs from healthy cows produced more milk, required less medica- tion and consumed more feed after treat- ment for the condition.
This process has not been widely explored in pigs due to the mo- nogastric gastrointesti- nal tract, but is there potential in the future?
SWINE breeding pro- grams have traditionally been focused on produc- tion efficiencies (that is, growth rate and feed conversion) and leanness of the carcass.
This focus has led to dramatic improvements in production efficiency and feed conversion.
More recently, the mar- ket is starting to shift in that marbling and meat quality are growing in im- portance for consumers, packers and processors.
There is much debate about whether selecting on marbling is detrimental to production traits, causing pigs to be inefficient.
It has been shown that pork quality traits are low to moderately heritable and difficult to measure, while carcass composition traits are highly heritable and easy to measure.
However, relationships between pork quality and production traits/carcass composition are not as clear.
Genetic improvement of production traits, carcass composition and meat quality requires under- standing the genetic con- trol of these traits.
Meat quality traits such as colour and marbling can be difficult and expensive to measure (because they have to be measured on a
carcass), however newer technologies such as ultra- sound make it possible to measure intramuscular fat as an indicator of carcass marbling.
Understanding the genetic control of meat quality traits and their re- lationship with production traits and carcass compo- sition is needed to imple- ment a successful breed- ing strategy that incorpo- rates pork quality.
A study by Miar et al. (2014) estimated genetic and phenotypic parame- ters between performance traits with meat quality and carcass characteris- tics in commercial pigs.
It was concluded that se- lection for weight coming out of the nursery would improve pork quality traits.
Average daily gain,
which is one of the main selection criteria in genet- ic programs, had no sig- nificant genetic correla- tions with any of the pork quality traits, indicating deterioration of pork qual- ity was not occurring.
Selection for marbling will slightly improve other pork quality traits (colour and pH) but selection for feed conversion decreases pork quality by making pork lighter in colour.
Further, selection for leaner carcasses will in- crease cooking loss and paleness of hams.
This indicates that if pork quality is not empha- sised in the genetic pro- gram, then the eating ex- perience will deteriorate.
The question – Can you include marbling in your selection program and
still improve production traits? – is verified by the work of Miar.
Marbling is one of the most important appear- ance factors used by consumers to evaluate the quality of fresh pork, along with colour.
So, if we produce pork that no one wants to eat, how will we ever change demand?
Having a long-term vi- sion of where a genetic program needs to go is a balance of production traits, carcass composition and pork quality.
As consumers continue to pay more attention to the eating experience of pork, it is critical to have pork quality as part of the selection objective.
Derek Petry GenesusInc.
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Page 14 – Australian Pork Newspaper, April 2018
www.porknews.com.au