Bio-economics for Pigs

Dr. Joe Rogowsky

Director of Health and Biosecurity


“It is not the strongest or the most intelligent who will survive but those who can best manage change.”- Charles Darwin. Shaped by nature over millions of years, by domestication over thousands of years and by intense genetic selection over the past few decades, the pigs that can best manage change are the genetics of choice. The better we understand the biology of the Genesus pig, the better we can help them stay healthy and reach their amazing genetic potential.

As I listen to the pig health concerns raised at the farms I visit, I am constantly reminded that pig biology is governed by the economics of supply and demand, and a prioritization for the allocation of resources. And understanding that goes a long way in problem solving. In my experience it appears maintenance is priority one (survival), immunity second (survival), growth third (survival/ approaching reproduction), pregnancy fourth (first investment in reproduction), udder development fifth (final investment in reproduction) and any surplus is stored in reserves.

Suffice it to say there is an internal resource management system (RMS) that manages all this. In gilts and weaned sows preparing to come into heat, the RMS does a credit check just the last week prior to estrus to determine if there’s enough equity and enough dependable income to commit to reproduction. So body condition and flush feeding pre-breed are the two main drivers for coming into heat, the number and maturity of the eggs at ovulation and the trajectory of pregnancy hormone levels. That, in turn, drives the number and quality of embryos that implant in the uterus, farrowing rate and the number and quality of piglets born. Nutritionists understand the demand and as long as we provide enough supply, we’re good to go.

However, unlike a loan with equal payments amortized over the length of the term, the demand for reproduction escalates rapidly after day 85 of gestation as fetal growth and udder development ramps up. If we don’t adjust the late gestation supply accordingly, the RMS will continue to allocate resources by priority which can result in abortions if chilled or vaccinated, mortality of the weakest fetuses (mummies), intrauterine growth retardation (uneven litters), premature farrowings (preemies), lower colostrum and milk supply, and oxidative stress causing lower lactation feed intakes, sick sows and excess body condition loss during lactation and the negative impact that has on re-breeding. Providing enough supply after day 85 of gestation and sustaining that right up to farrowing is critical to support this stage.

From a newborn piglet’s perspective, maintenance is priority one. They have to adjust from a comfortable 38-39°C in the womb to a relatively cool, drafty environment while wet, from passive to active nutrition and now having to compete with its littermates to survive. Priority two is loading up on maternal immunity, both in the form of antibodies as well as immune cells, some already pathogen-specific. Sustaining adequate feed intakes prior to farrowing drives the amount of colostrum available and feed intakes during lactation supports milk supply. The degree the piglets are comfortable and healthy will determine the amount of resources then allocated for growth.

Post weaning health (immunity) and growth performance is also driven by how well we meet the demand for resources for maintenance. Interruptions in nutrient supply at weaning, when moved, mixed, overcrowded, out of feed or water, diets or taste change, etc, as well as increases in nutrient demand when chilled, heat stressed and vaccinated, all cause a shift of resources to maintenance and away from immunity and growth. Good to know.

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This post was written by Genesus