The Pig Phosphorus Puzzle: How Feed Intake Impacts Nutrient Absorption

Rhea Morgan in Health & Wellness August 2025 • 4 min read.

"Unlocking the secrets of phosphorus digestibility in growing pigs to optimize feed efficiency and reduce environmental impact."

In modern pig farming, maximizing nutrient absorption from feed is crucial for both animal health and environmental sustainability. Phosphorus (P) is a key nutrient, vital for bone development and various metabolic processes. However, the efficiency with which pigs absorb phosphorus can vary, influenced by factors such as the amount of feed they consume.

Recent research has explored how different levels of feed intake (FI) affect the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of phosphorus in growing pigs. Understanding these dynamics is essential for formulating diets that not only meet the pigs' nutritional needs but also minimize phosphorus excretion, a major contributor to water pollution.

This article breaks down the findings of a detailed study investigating the interplay between feed intake, dietary phosphorus levels, and phosphorus digestibility in growing pigs. We'll explore how these factors interact to influence nutrient absorption and what practical implications these findings have for pig farmers.

Decoding Phosphorus Digestibility: The Feed Intake Factor

Stylized pig surrounded by glowing phosphorus molecules, symbolizing efficient nutrient absorption.

A recent study investigated how feed intake influences phosphorus digestibility in pigs, focusing on diets with varying phosphorus concentrations. Researchers used seventy-two barrows, dividing them into groups fed different diets (P-free, low-P, and moderate-P) and varying feed intake levels (3%, 4%, and 5% of body weight per day). The goal was to measure how efficiently the pigs absorbed phosphorus under these different conditions.

The study revealed a few key insights:

Feed Intake Matters: The amount of feed pigs consume directly affects how well they absorb phosphorus.
Low-P vs. Moderate-P Diets: In pigs fed low-phosphorus diets, changing the amount of feed didn't significantly alter phosphorus absorption. However, in pigs fed moderate-phosphorus diets, increasing feed intake led to decreased phosphorus absorption.
Dietary P Level is Key: How pigs respond to different feed intake levels depends on the phosphorus content of their diet.

Specifically, the study found that with moderate-P diets, as feed intake increased, the ATTD and STTD of phosphorus decreased. This suggests that pigs may have a harder time efficiently absorbing phosphorus when they consume larger amounts of a moderate-phosphorus feed. The impact of feed intake on phosphorus absorption was less pronounced in the low-P diet group.

Practical Takeaways: Optimizing Phosphorus Use in Pig Farming

The research underscores that feed intake level is a critical factor influencing phosphorus digestibility in growing pigs, particularly when they are fed moderate-phosphorus diets. Farmers need to be aware of these interactions to fine-tune their feeding strategies.

These findings support the idea that carefully balancing feed intake and phosphorus levels in pig diets can lead to more efficient nutrient utilization. This not only benefits the animals' health and growth but also reduces phosphorus excretion, contributing to more sustainable farming practices.

Future research should focus on identifying the optimal balance of feed intake and dietary phosphorus levels to maximize nutrient absorption while minimizing environmental impact. By implementing these strategies, the pork industry can move towards more sustainable and efficient production methods.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.anifeedsci.2018.10.012, Alternate LINK

Title: Effect Of Feed Intake Level On The Determination Of Apparent And Standardized Total Tract Digestibility Of Phosphorus For Growing Pigs

Subject: Animal Science and Zoology

Journal: Animal Feed Science and Technology

Publisher: Elsevier BV

Authors: J.B. Liu, H.L. Yan, S.C. Cao, J. Liu, H.F. Zhang

Published: 2018-12-01

Everything You Need To Know

Why is understanding phosphorus digestibility important in pig farming?

In modern pig farming, phosphorus is crucial for bone development and metabolic processes. The efficiency of phosphorus absorption in pigs is influenced by feed intake. Recent research focuses on how different feed intake levels affect apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of phosphorus in growing pigs. Understanding these dynamics is essential for formulating diets and minimize phosphorus excretion.

How was the impact of feed intake on phosphorus absorption studied in growing pigs?

The study used seventy-two barrows, divided into groups fed diets with varying phosphorus content (P-free, low-P, and moderate-P) and different feed intake levels (3%, 4%, and 5% of body weight per day). Researchers measured how efficiently the pigs absorbed phosphorus under these different conditions.

What were the key findings regarding the relationship between feed intake, dietary phosphorus levels, and phosphorus absorption?

The research indicates that the amount of feed pigs consume affects how well they absorb phosphorus. In pigs fed low-phosphorus diets, changes in feed intake didn't significantly alter phosphorus absorption. However, in pigs fed moderate-phosphorus diets, increasing feed intake led to decreased apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of phosphorus. Thus, the phosphorus content of their diet impacts how pigs respond to different feed intake levels.

What practical implications does the research on feed intake and phosphorus digestibility have for pig farmers?

The research highlights that feed intake level influences phosphorus digestibility, especially with moderate-phosphorus diets. As feed intake increased, the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of phosphorus decreased, indicating pigs may have difficulty absorbing phosphorus when consuming larger amounts of moderate-phosphorus feed. This suggests that optimizing feeding strategies is crucial to maximizing nutrient use and reducing phosphorus excretion.

Besides feed intake, what other factors might influence phosphorus absorption in pigs, and how could future research explore these?

While the study focuses on the relationship between feed intake and phosphorus digestibility, other factors influencing phosphorus absorption in pigs include the source of phosphorus in the diet (organic vs. inorganic), the presence of phytase (an enzyme that helps break down phytate, a form of phosphorus indigestible to pigs), and the age and health of the pigs. Further research could explore these interactions to develop even more precise feeding strategies.